1. Field of the Invention
The invention relates to a chain conveyor or chain line of an endless roller chain of a fabric web stretching machine or tenter frame or the like, including stretching or tentor means at each chain link, a guide rail for the forward running part of the chain, chain wheels forming transitions to the backward running part of the chain with teeth engaging the chain at the longitudinal ends of the guide rail, the guide rail forming a support for horizontally directed transverse forces to be exerted on the fabric web, each of the stretching or tenter means having a transverse force roller for transferring transverse forces, the transverse force rollers being supported on roller bearings about a vertical axis coaxial to the associated chain bolt absorbing longitudinal chain forces, and the transverse force rollers abutting the outer surface of the guide rail facing away from the fabric web.
2. Description of the Related Art
In stretching or tenter machines of this type, manufactured and sold by A. Monforts GmbH and Co., Monchengladbach, Federal Republic of Germany, a web of textile material is supported at the longitudinal edges thereof and is normally moved through a heat treatment area while being laterally stretched. A so-called chain conveyor or chain line is normally provided parallel to each of the longitudinal edges of the fabric web as stretching or tenter and fastening means in a machine which is generally known as a stretching machine or tenter frame. An endless roller chain moves in each of these chain conveyors or chain lines and has stretching or tenter means for fastening the fabric web. Needles and/or clips are used as stretching or tenter means. The roller chains are turned around at the input and the output sides of the machine. Each chain is propelled by one guide roller, which is normally in the form of a chain wheel at the output side of the machine.
Besides the chain wheels, a rail for the roller chain supporting the weight of the chains and at least one guide rail supporting the lateral forces created by the tentered fabric web, are associated with the chain conveyor or chain line. The lateral forces act perpendicularly to the tractive force which acts in the longitudinal direction of the chain from the chain drive.
According to German Published, Prosecuted Application DE-AS 14 60 640, if the stretching or tenter means are each provided with at least two transverse force rollers located at the side of the chain bolts, and if these rollers abut both longitudinal sides of the guide rail, the guide rail at the chain turning point at the input side of the machine extends uninterruptedly from the forward running part to the backward running part of this point. In this way, impact or shock points along the chain conveyor or chain line are avoided or limited to the degree absolutely necessary for the drive. However, the expenditure and effort required in connection with the known apparatus is considerable, because the chain bolts cannot be used as supports for the transverse force rollers and furthermore, additional rollers must be provided at each stretching or tenter means just for turning.
However, this large effort was necessary heretofore because it made it possible to avoid the polygonal movement of the chain encountered at the return of the chain. Especially during the high chain speeds of 200 m/min which are strived for, the polygonal movement causes very strong flapping of the chain and makes it difficult or impossible to catch the edges of the fabric web in the area where it is placed on the needles or clips. At the output side of the machine, the polygonal movement can also make the removal from the needles or clips more difficult and eventually prevent a straight cutting of the edge. Therefore, in the past it was often necessary either to utilize larger guide rollers corresponding to the increased machine speed or to install expensive dampers which are subject to wear, in order to reduce the polygonal movement. However, it is desirable, especially at the input side of the machine, to provide guide rollers which are as small as possible, so that the distance from the last guide drum before the chain to the point where the web is put on needles or clips is as short as possible and a turning in or turning over of the loose edges of the web is avoided in this area. The dampers are also unsatisfactory, especially at higher machine speeds, due to their performance as well as because of the wear and the noise generation connected therewith.